The Russian Orthodox Church has officially added the celebration of St. Patrick to its calendar, but the holiday will be honored on March 30. Adding to the confusion, Moscow has already been marking the holiday on its traditional date of March 17 for 25 years.

The discrepancy is because the Orthodox Church follows the Julian calendar, which runs 13 days behind the Gregorian calendar, RT.com reports. For example, Russians and Orthodox Christians following the calendar celebrate Christmas on January 7 instead of December 25.

Ireland’s patron saint was already venerated in the Orthodox tradition, but now the Holy Synod of the Russian Orthodox Church has decided that St. Patrick, along with many other Western saints, is to be honored with a separate day in the ecclesiastical calendar.

Moscow Patriarchy spokesman Vladimir Legoyda told Russian media: “In total, more than a dozen of saints who had struggled in Central and Western Europe before 1054 were added to the Menologion. They include saint Patriky, the Enlightener of Ireland, better known among the faithful of our country as Saint Patrick.”

Many Russians already celebrate St Patrick’s Day, which is meant to mark the date of the saint’s supposed death.

Following the collapse of the Iron Curtain, business ties were created between Dublin and Moscow during perestroika, including Russia’s first-ever duty free shop in Sheremetyevo Airport. Many Russians embraced Irish culture and the global celebration of St Patrick’s Day, reports RT.com. In 1992, Moscow sanctioned a first official St. Patrick’s Day’s parade.

Today, Russians in cities like St. Petersburg, Nizhny Novgorod, Kazan, Chelyabinsk, Novosibirsk, and Khabarovsk mark the Irish holiday with Irish music and Irish dance,and drink pints of Guinness in Irish pubs found all across the country.

The official Moscow parade is just one of the highlights of the city’s St Patrick’s Week. The “week” spans 10-14 days and encompasses Irish music, dance, and film festivals.